How to install a porch light

Go to your local hardware store.
Spend 30 minutes examining at all the selections while your 3yo "helpfully" picks out lights at random.
Finally find the one you want in the right price category.
Take it home.
Open box.
Discover it's missing a part.
Take it back.
Find another box of the same light.
Open the box before you leave, making sure it has the missing part.
Take it home.
Open box.
Discover it's missing a different part.
Go to bed.

Take it back the next day.
Get spotted by an employee who asks why you keep showing up.
Explain.
Have a good laugh.
Open the new box before you leave, making sure it has BOTH the missing parts.
Take it home.
Open box.
Yank old porch light off the wall and vacuum up the dead carcasses and debris from the last 20+ years, amazed they never set off a fire.
Install new mounting plate, deciding not to worry that it's too big and you can only drive in one screw.
Attach white wires to white wires.
Attach black wires to black wires.
Attach grounding wire.
Attach light to mounting plate.
Discover the part that was missing from the first box, that you thought was in this box, is actually a useless screw.
Curse.
Maybe curse again.
Decide it doesn't effing matter and vow to go steal the correct part next time you're at the hardware store.
Hope that same employee doesn't see you.

Congratulations, you have installed a porch light! 
You deserve a mojito!
Drink two.

porch light, on again